More than 50 per cent of all homes across the nation lost value in June. The slump is affecting the top end of the market as well as the lower end.

Residex chief executive John Edwards is warning of tough times ahead. "It looks like we're moving into a one-in-100-year event," Mr Edwards said.

"It points to a situation where unless the Government and Reserve Bank take action Australia could move into a recession.

"The only other times this has ever occurred are before we have moved into severe recessions."

The Residex statistics come at the end of a gloomy week for the Australian economy. Official figures released last week showed housing construction declined for a fourth consecutive month and demand for loans fell 23 per cent in the four months to the end of May.

Higher petrol prices and interest rates, and the share market slump also saw consumer confidence drop 51 per cent to its lowest level since 1992, when the economy was recovering from recession.

Mr Edwards said housing markets in different states usually rose and fell at different times.

"To see an adjustment going on a wholesale basis across the whole of the nation is incredibly unusual," he said. "Never in my lifetime have I seen so many converging negative events."

Residex reports the current median house value in Sydney is $573,000, down 1.05 per cent in June compared with 1.81 per cent for three months to the end of June.

RP Data's director of property research Tim Lawless said what happened in the coming months would depend on inflation.

He showed some optimism, although he said values would probably fall further this year.

"Coming into 2009, it's likely - and it depends on what happens with interest rates - we will start to see some value improvements return to the market, albeit relatively small," he said.